Autologous blood transfusions, which are defined as the reinfusion of the patient's own blood, continue to be used in surgical settings. One type of autologous blood transfusion involves preoperative donation and storage of a patient's blood. In such a process, a patient's blood is collected, typically over a period of weeks or months, and stored for transfusion at the time of surgery. While preoperative autologous blood donation/transfusion is popular, the process suffers from some drawbacks. These drawbacks can include limitations in the amount of blood that can be collected over a period of time, wasting of pre-donated blood because it is not needed or expired, and transfusion of the wrong blood due to clerical errors.
In response to these shortcomings, intraoperative hemodilution (also referred to as autologous normovolemic hemodilution or ANH) has grown in popularity. ANH includes the removal or collection of blood (typically just before or at the start of a surgical procedure) with the simultaneous infusion of appropriate cell-free solution(s) to maintain intravascular volume prior to surgical blood loss. The previously collected patient's blood is reinfused during or after surgery, as needed, to maintain a desired post-ANH hemoglobin concentration. Typically, the anesthesiologist is responsible for the ANH procedure. ANH allows for collection and reinfusion of a greater volume of blood than preoperative autologous procedures because the patient is typically sedated and often is on a ventilator. ANH reduces red blood cell loss because the blood lost during surgery has a lower hematocrit (the percentage of whole blood that is comprised of red blood cells).
Conventional devices used for ANH typically include a standard blood donation/transfer bag, e.g., a 500 cc bag, and rely on gravity for blood drainage and collection. Such conventional transfer bag devices require long tubing to create the necessary siphon gradient for blood drainage. In order to accommodate the long tubing, the bags are often placed far away from the patient making it more difficult to monitor the progress of the blood drainage. This can be problematic for several reasons. The use of long tubing increases the likelihood of clotting within the tubing. Having the bag out of sight increases the chances of collecting too much blood in a single bag, which could cause clotting, forgetting to agitate the bag periodically to mix the collected blood with an anticoagulant within the bag, and potentially knocking over the bag or pulling the line out of the bag and/or patient.